Method and system for stabilizing a payload

ABSTRACT

An apparatus includes a carrier, one or more first sensors, one or more second sensors, and one or more processors. The carrier includes a first frame and a second frame. A payload is affixed to the first frame. The second frame is rotatably coupled to a movable object. The one or more first sensors are disposed on the payload and configured to measure one or more motion characteristics of the payload. The one or more second sensors are disposed on the carrier and configured to measure one or more motion characteristics of the carrier. The one or more processors are configured to determine an input torque based on the one or more motion characteristics of the payload, determine an estimated disturbance torque based on the one or more motion characteristics of the carrier, and calculate an output torque based on the input torque and the estimated disturbance torque.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Application No.PCT/CN2016/074729, filed on Feb. 26, 2016, the entire contents of whichare incorporated herein by reference.

BACKGROUND OF THE DISCLOSURE

Unmanned vehicles such as unmanned aerial vehicles (UAVs) can be usedfor performing surveillance, reconnaissance, and exploration tasks for awide variety of civilian, commercial, and military applications. A UAVmay be manually controlled by a remote user, or may operate in asemi-autonomous or fully autonomous manner. Such UAVs can include acarrier used to support payloads such as cameras for obtaining imagedata of a target object.

Prior approaches for controlling a payload carried by a UAV may not beoptimal in some instances. For instance, prior methods for stabilizing apayload may not be adapted to compensate for external disturbances tothe carrier and payload and may not account for the specific mechanicalcharacteristics of the carrier, which may reduce the accuracy of controlof the payload.

SUMMARY OF THE DISCLOSURE

The present disclosure provides systems, methods, and devices related tothe control and operation of a carrier for supporting a payload for amovable object such as an unmanned aerial vehicle (UAV). In someembodiments, a carrier is used to mechanically couple a payload to amovable object and control the position and/or orientation of thepayload relative to the movable object. However, during operation, thecarrier may be subject to external disturbances (e.g., wind, temperaturechanges, external impacts, etc.) that may affect the carrierconfiguration. Additionally, the motion characteristics of differenttypes of carriers and payloads may influence their response toactuation. The embodiments disclosed herein can estimate and compensatefor such factors, thus improving the accuracy of controlling the payloadposition and/or orientation using the carrier.

In one aspect, a method for controlling an attitude of a payload isprovided, the method comprising: determining an input torque based on aninput angle and one or more motion characteristics of the payload,wherein the input angle is associated with a desired attitude of thepayload; determining an estimated disturbance torque based on one ormore motion characteristics of a carrier to which the payload iscoupled, wherein the estimated disturbance torque is associated with adisturbance to the carrier; and calculating an output torque based onthe input torque and the estimated disturbance torque, wherein theoutput torque is used to effect movement of the carrier to achieve thedesired attitude of the payload.

In some embodiments, the carrier is rotatably coupled to a movableobject for supporting the carrier.

In some embodiments, the carrier is a multi-axis gimbal.

In some embodiments, the movable object is a UAV.

In some embodiments, the carrier is configured to rotate relative to themovable object about one or more rotational axes. The output torque canbe applied about the one or more rotational axes.

In some embodiments, the carrier comprises a plurality of framescomprising at least a first frame and a second frame. The payload can beaffixed to the first frame. The second frame can be rotatably coupled tothe movable object. The second frame can be configured to rotate about ayaw axis.

In some embodiments, the second frame is coupled to the movable objectvia a damping element.

In some embodiments, the payload is serially connected to the movableobject by the first frame and the second frame. The second frame can becoupled between the movable object and the first frame.

In some embodiments, the one or more motion characteristics of thecarrier comprise at least a linear acceleration or an angularacceleration of the second frame. The one or more motion characteristicsof the second frame can be measured using one or more sensors located inproximity to the second frame. The one or more sensors can comprise atleast one of an accelerometer or a gyroscope.

In some embodiments, the one or more sensors are further configured tomeasure one or more motion characteristics of the second frame whencoupled to the movable object via a damping element. The damping elementcan be configured to reduce an effect of the disturbance on the secondframe. The damping element can be configured to absorb vibration of thesecond frame. The one or more sensors can be directly disposed on acoupling structure connecting the damping element to the second frame.The one or more sensors can be provided on a flexible printed circuit(FPC) attached onto the coupling structure. The one or more sensors canbe positioned along an axis of rotation of the second frame.

In some embodiments, the output torque is applied via an actuatorcoupled to the second frame. The actuator can be a motor comprising arotor and a stator. The rotor can be coupled to the second frame and thestator can be coupled to the movable object.

In some embodiments, the one or more motion characteristics of thecarrier are measured using an inertial sensor disposed on a frame of thecarrier. The estimated disturbance torque can be determined by arotation matrix transformation comprising measurements of the one ormore motion characteristics of the carrier.

In some embodiments, the input angle is provided by a user using anexternal device in communication with the payload.

In some embodiments, the input angle is provided to one or moreprocessors in a motion controller on the payload. The motion controllercan be configured to calculate the output torque based on the inputtorque and the estimated disturbance torque. The motion controller canbe configured to control an actuator that is coupled to the carrier torotate at the output torque, so as to effect the movement of the carrierto achieve the desired attitude of the payload.

In some embodiments, the one or more motion characteristics of thepayload comprise at least one of an instantaneous attitude, aninstantaneous position, an angular velocity, a linear velocity, anangular acceleration, or a linear acceleration of the payload. The oneor more motion characteristics of the payload can be measured using oneor more sensors located on the payload. The one or more sensors cancollectively constitute an inertial measurement unit (IMU).

In some embodiments, the disturbance comprises one or more of windeffects, temperature changes, or external impact to the payload or thecarrier.

In some embodiments, the estimated disturbance torque is determined byinputting one or more motion characteristics of a damping element into apredefined dynamics-based model of the carrier. The damping element canbe disposed between the movable object and a frame of the carrier. Theone or more motion characteristics of the damping element can bemeasured using one or more sensors disposed on the damping element. Theone or more sensors can be provided on a flexible printed circuit (FPC)attached onto the damping element. The one or more motioncharacteristics of the damping element can comprise at least a linearacceleration or an angular acceleration of the damping element. The oneor more motion characteristics of the damping element can be associatedwith the one or more motion characteristics of the frame.

In some embodiments, the estimated disturbance torque is calculated withrespect to a rotatable joint on a frame of the carrier and the rotatablejoint is configured to couple the frame to the movable object.

In some embodiments, the method further comprises: further refining theestimated disturbance torque using a proportional-derivative (PD)controller. The estimated disturbance torque can be refined by applyingone or more filters to the estimated disturbance torque. The method canfurther comprise: calculating the output torque based on the inputtorque and the refined disturbance torque.

In some embodiments, the input torque is determined using a feedbackcontrol loop. The feedback control loop can be implemented using atleast one proportional-derivative (PD) controller. A first PD controllercan be configured to calculate an input angular velocity based on adifference between an instantaneous angle measured by one or moresensors on the payload and the input angle. A second PD controller canbe configured to calculate the input torque based on a differencebetween an instantaneous angular velocity measured by the one or moresensors on the payload and the input angular velocity.

In some embodiments, the output torque is calculated by compensating theinput torque with the estimated disturbance torque. The output torquecan be calculated by subtracting the estimated disturbance torque fromthe input torque. The output torque can be used in conjunction with anactual disturbance torque from the disturbance to effect the movement ofthe carrier, so as to achieve the desired attitude of the payload. Theactual disturbance torque can be applied to a frame of the carriercoupled to the movable object.

In another aspect, an apparatus for controlling an attitude of a payloadis provided, the apparatus comprising one or more processors that are,individually or collectively, configured to: determine an input torquebased on an input angle and one or more motion characteristics of thepayload, wherein the input angle is associated with a desired attitudeof the payload; determine an estimated disturbance torque based on oneor more motion characteristics of a carrier to which the payload iscoupled, wherein the estimated disturbance torque is associated with adisturbance to the carrier; and calculate an output torque based on theinput torque and the estimated disturbance torque, herein the outputtorque is used to effect movement of the carrier to achieve the desiredattitude of the payload.

In some embodiments, the carrier is rotatably coupled to a movableobject for supporting the carrier.

In some embodiments, the carrier is a multi-axis gimbal.

In some embodiments, the movable object is a UAV.

In some embodiments, the carrier is configured to rotate relative to themovable object about one or more rotational axes. The output torque canbe applied about the one or more rotational axes.

In some embodiments, the carrier comprises a plurality of framescomprising at least a first frame and a second frame. The payload can beaffixed to the first frame. The second frame can be rotatably coupled tothe movable object. The second frame can be configured to rotate about ayaw axis.

In some embodiments, the second frame is coupled to the movable objectvia a damping element.

In some embodiments, the payload is serially connected to the movableobject by the first frame and the second frame. The second frame can becoupled between the movable object and the first frame.

In some embodiments, the one or more motion characteristics of thecarrier comprise at least a linear acceleration or an angularacceleration of the second frame. The one or more motion characteristicsof the second frame can be measured using one or more sensors located inproximity to the second frame. The one or more sensors can comprise atleast one of an accelerometer or a gyroscope.

In some embodiments, the one or more sensors are further configured tomeasure one or more motion characteristics of the second frame whencoupled to the movable object via a damping element. The damping elementcan be configured to reduce an effect of the disturbance on the secondframe. The damping element can be configured to absorb vibration of thesecond frame. The one or more sensors can be directly disposed on acoupling structure connecting the damping element to the second frame.The one or more sensors can be provided on a flexible printed circuit(FPC) attached onto the coupling structure. The one or more sensors canbe positioned along an axis of rotation of the second frame.

In some embodiments, the output torque is applied via an actuatorcoupled to the second frame. The actuator can be a motor comprising arotor and a stator. The rotor can be coupled to the second frame and thestator can be coupled to the movable object.

In some embodiments, the one or more motion characteristics of thecarrier are measured using an inertial sensor disposed on a frame of thecarrier. The estimated disturbance torque can be determined by arotation matrix transformation comprising measurements of the one ormore motion characteristics of the carrier.

In some embodiments, the input angle is provided by a user using anexternal device in communication with the payload.

In some embodiments, the input angle is provided to one or moreprocessors in a motion controller on the payload. The motion controllercan be configured to calculate the output torque based on the inputtorque and the estimated disturbance torque. The motion controller canbe configured to control an actuator that is coupled to the carrier torotate at the output torque, so as to effect the movement of the carrierto achieve the desired attitude of the payload.

In some embodiments, the one or more motion characteristics of thepayload comprise at least one of an instantaneous attitude, aninstantaneous position, an angular velocity, a linear velocity, anangular acceleration, or a linear acceleration of the payload. The oneor more motion characteristics of the payload can be measured using oneor more sensors located on the payload. The one or more sensors cancollectively constitute an inertial measurement unit (IMU).

In some embodiments, the disturbance comprises one or more of windeffects, temperature changes, or external impact to the payload or thecarrier.

In some embodiments, the estimated disturbance torque is determined byinputting one or more motion characteristics of a damping element into apredefined dynamics-based model of the carrier. The damping element canbe disposed between the movable object and a frame of the carrier. Theone or more motion characteristics of the damping element can bemeasured using one or more sensors disposed on the damping element. Theone or more sensors can be provided on a flexible printed circuit (FPC)attached onto the damping element. The one or more motioncharacteristics of the damping element can comprise at least a linearacceleration or an angular acceleration of the damping element. The oneor more motion characteristics of the damping element can be associatedwith the one or more motion characteristics of the frame.

In some embodiments, the estimated disturbance torque is calculated withrespect to a rotatable joint on a frame of the carrier and the rotatablejoint is configured to couple the frame to the movable object.

In some embodiments, the one or more processors are configured tofurther refine the estimated disturbance torque using aproportional-derivative (PD) controller. The estimated disturbancetorque can be refined by applying one or more filters to the estimateddisturbance torque. The one or more processors can be configured tocalculate the output torque based on the input torque and the refineddisturbance torque.

In some embodiments, the input torque is determined using a feedbackcontrol loop. The feedback control loop can be implemented using atleast one proportional-derivative (PD) controller. A first PD controllercan be configured to calculate an input angular velocity based on adifference between an instantaneous angle measured by one or moresensors on the payload and the input angle. A second PD controller canbe configured to calculate the input torque based on a differencebetween an instantaneous angular velocity measured by the one or moresensors on the payload and the input angular velocity.

In some embodiments, the output torque is calculated by compensating theinput torque with the estimated disturbance torque. The output torquecan be calculated by subtracting the estimated disturbance torque fromthe input torque. The output torque can be used in conjunction with anactual disturbance torque from the disturbance to effect the movement ofthe carrier, so as to achieve the desired attitude of the payload. Theactual disturbance torque can be applied to a frame of the carriercoupled to the movable object.

In another aspect, a non-transitory computer-readable medium storinginstructions is provided. The instructions, when executed, cause acomputer to perform a method for controlling an attitude of a payload,the method comprising: determining an input torque based on an inputangle and one or more motion characteristics of the payload, wherein theinput angle is associated with a desired attitude of the payload;determining an estimated disturbance torque based on one or more motioncharacteristics of a carrier to which the payload is coupled, whereinthe estimated disturbance torque is associated with a disturbance to thecarrier; and calculating an output torque based on the input torque andthe estimated disturbance torque, wherein the output torque is used toeffect movement of the carrier to achieve the desired attitude of thepayload.

In another aspect, a system for controlling an attitude of a payload isprovided, the system comprising: a movable object; a carrier configuredto couple the payload to the movable object; and one or more processorsthat are, individually or collectively, configured to: determine aninput torque based on an input angle and one or more motioncharacteristics of the payload, wherein the input angle is associatedwith a desired attitude of the payload; determine an estimateddisturbance torque based on one or more motion characteristics of acarrier to which the payload is coupled, wherein the estimateddisturbance torque is a result of a disturbance to the carrier; andcalculate an output torque based on the input torque and the estimateddisturbance torque, wherein the output torque is used to effect movementof the carrier to achieve the desired attitude of the payload.

In some embodiments, the carrier is rotatably coupled to the movableobject for supporting the carrier.

In some embodiments, the carrier is a multi-axis gimbal.

In some embodiments, the movable object is a UAV.

In some embodiments, the carrier is configured to rotate relative to themovable object about one or more rotational axes. The output torque canbe applied about the one or more rotational axes.

In some embodiments, the carrier comprises a plurality of framescomprising at least a first frame and a second frame. The payload can beaffixed to the first frame. The second frame can be rotatably coupled tothe movable object. The second frame can be configured to rotate about ayaw axis.

In some embodiments, the second frame is coupled to the movable objectvia a damping element.

In some embodiments, the payload is serially connected to the movableobject by the first frame and the second frame. The second frame can becoupled between the movable object and the first frame.

In some embodiments, the one or more motion characteristics of thecarrier comprise at least a linear acceleration or an angularacceleration of the second frame. The one or more motion characteristicsof the second frame can be measured using one or more sensors located inproximity to the second frame. The one or more sensors can comprise atleast one of an accelerometer or a gyroscope.

In some embodiments, the one or more sensors are further configured tomeasure one or more motion characteristics of the second frame whencoupled to the movable object via a damping element. The damping elementcan be configured to reduce an effect of the disturbance on the secondframe. The damping element can be configured to absorb vibration of thesecond frame. The one or more sensors can be directly disposed on acoupling structure connecting the damping element to the second frame.The one or more sensors can be provided on a flexible printed circuit(FPC) attached onto the coupling structure. The one or more sensors canbe positioned along an axis of rotation of the second frame.

In some embodiments, the output torque is applied via an actuatorcoupled to the second frame. The actuator can be a motor comprising arotor and a stator. The rotor can be coupled to the second frame and thestator can be coupled to the movable object.

In some embodiments, the one or more motion characteristics of thecarrier are measured using an inertial sensor disposed on a frame of thecarrier. The estimated disturbance torque can be determined by arotation matrix transformation comprising measurements of the one ormore motion characteristics of the carrier.

In some embodiments, the input angle is provided by a user using anexternal device in communication with the payload.

In some embodiments, the input angle is provided to one or moreprocessors in a motion controller on the payload. The motion controlleran be configured to calculate the output torque based on the inputtorque and the estimated disturbance torque. The motion controller canbe configured to control an actuator that is coupled to the carrier torotate at the output torque, so as to effect the movement of the carrierto achieve the desired attitude of the payload.

In some embodiments, the one or more motion characteristics of thepayload comprise at least one of an instantaneous attitude, aninstantaneous position, an angular velocity, a linear velocity, anangular acceleration, or a linear acceleration of the payload. The oneor more motion characteristics of the payload can be measured using oneor more sensors located on the payload. The one or more sensors cancollectively constitute an inertial measurement unit (IMU).

In some embodiments, the disturbance comprises one or more of windeffects, temperature changes, or external impact to the payload or thecarrier.

In some embodiments, the estimated disturbance torque is determined byinputting one or more motion characteristics of a damping element into apredefined dynamics-based model of the carrier. The damping element canbe disposed between the movable object and a frame of the carrier. Theone or more motion characteristics of the damping element can bemeasured using one or more sensors disposed on the damping element. Theone or more sensors can be provided on a flexible printed circuit (FPC)attached onto the damping element. The one or more motioncharacteristics of the damping element can comprise at least a linearacceleration or an angular acceleration of the damping element. The oneor more motion characteristics of the damping element can be associatedwith the one or more motion characteristics of the frame.

In some embodiments, the estimated disturbance torque is calculated withrespect to a rotatable joint on a frame of the carrier and the rotatablejoint is configured to couple the frame to the movable object.

In some embodiments, the method further comprises: further refining theestimated disturbance torque using a proportional-derivative (PD)controller. The estimated disturbance torque can be refined by applyingone or more filters to the estimated disturbance torque. The method canfurther comprise: calculating the output torque based on the inputtorque and the refined disturbance torque.

In some embodiments, the input torque is determined using a feedbackcontrol loop. The feedback control loop can be implemented using atleast one proportional-derivative (PD) controller. A first PD controllercan be configured to calculate an input angular velocity based on adifference between an instantaneous angle measured by one or moresensors on the payload and the input angle. A second PD controller canbe configured to calculate the input torque based on a differencebetween an instantaneous angular velocity measured by the one or moresensors on the payload and the input angular velocity.

In some embodiments, the output torque is calculated by compensating theinput torque with the estimated disturbance torque. The output torquecan be calculated by subtracting the estimated disturbance torque fromthe input torque. The output torque can be used in conjunction with anactual disturbance torque from the disturbance to effect the movement ofthe carrier, so as to achieve the desired attitude of the payload. Theactual disturbance torque can be applied to a frame of the carriercoupled to the movable object.

In another aspect, an apparatus for controlling an attitude of a payloadis provided, comprising: a carrier comprising at least a first frame anda second frame, wherein the payload is affixed to the first frame andthe second frame is rotatably coupled to a movable object; one or moresensors disposed on the payload, wherein the sensors are configured tomeasure one or more motion characteristics of the payload; one or moresensors disposed on the carrier, wherein the sensors are configured tomeasure one or more motion characteristics of the carrier; and one ormore processors that are, individually or collectively, configured to:determine an input torque based on the one or more motioncharacteristics of the payload; determine an estimated disturbancetorque based on the one or more motion characteristics of the carrier;and calculate an output torque based on the input torque and theestimated disturbance torque, wherein the output torque is configured toeffect movement of the second frame to achieve a desired attitude of thepayload.

In some embodiments, the carrier is a multi-axis gimbal.

In some embodiments, the apparatus further comprises the movable object.

In some embodiments, the apparatus further comprises a damping elementdisposed between the movable object and the carrier. The second framecan be coupled to the movable object via the damping element. The secondframe can be coupled to the damping element via a coupling structure,and the one or more sensors can be disposed on the coupling structure.The one or more sensors can be provided on a flexible printed circuit(FPC) attached onto the coupling structure. The damping element can beconfigured to reduce an effect of a disturbance on the carrier. Thedamping element can be configured to absorb vibration of the secondframe.

In some embodiments, the second frame is coupled to a motor configuredto rotate the second frame about a yaw axis and wherein the one or moresensors are disposed on the second frame or the motor.

In some embodiments, the estimated disturbance torque is determined byinputting one or more motion characteristics of the carrier into apredefined dynamics-based model of the carrier. The one or more motioncharacteristics of the carrier can comprise at least a linearacceleration or an angular acceleration of the carrier. The one or moremotion characteristics of the carrier can be associated with one or moremotion characteristics of the second frame.

In some embodiments, the estimated disturbance torque is calculated withrespect to a rotatable joint on the second frame, the rotatable jointconfigured to couple the second frame to the movable object.

In some embodiments, the estimated disturbance torque is further refinedusing a proportional-derivative (PD) controller. The estimateddisturbance torque can be refined by applying one or more filters to theestimated disturbance torque. The output torque can be calculated basedon the input torque and the refined disturbance torque.

In some embodiments, the input torque is determined using a feedbackcontrol loop. The feedback control loop can be implemented using atleast one proportional-derivative (PD) controller. A first PD controllercan be configured to calculate an input angular velocity based on adifference between an instantaneous angle measured by the one or moresensors on the payload and the input angle. A second PD controller canbe configured to calculate the input torque based on a differencebetween an instantaneous angular velocity measured by the one or moresensors on the payload and the input angular velocity.

In some embodiments, the output torque is calculated by compensating theinput torque with the estimated disturbance torque. The output torquecan be calculated by subtracting the estimated disturbance torque fromthe input torque. The output torque can be used in conjunction with anactual disturbance torque to effect the movement of the carrier, so asto achieve the desired attitude of the payload. The actual disturbancetorque can result from a disturbance to the carrier. The actualdisturbance torque can be applied to the second frame.

Other objects and features of the present disclosure will becomeapparent upon review of the specification, claims, and appended figures.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present disclosure will be obtained by reference tothe following detailed description that sets forth illustrativeembodiments, in which the principles of the disclosure are utilized, andthe accompanying drawings of which:

FIG. 1 illustrates a movable object, carrier, and payload, in accordancewith embodiments;

FIG. 2 illustrates an apparatus for controlling a payload, in accordancewith embodiments;

FIG. 3 illustrates a block diagram of a feedback loop for controlling apayload, in accordance with embodiments;

FIG. 4 illustrates an apparatus for controlling a payload, in accordancewith embodiments;

FIG. 5 illustrates a movable object, carrier, and payload, in accordancewith embodiments;

FIG. 6 illustrates an apparatus for controlling a payload including aninternal damping element, in accordance with embodiments;

FIG. 7 illustrates a block diagram of a feedback loop for controlling apayload, in accordance with embodiments;

FIG. 8 illustrates a method for controlling a payload, in accordancewith embodiments;

FIG. 9 illustrates an unmanned aerial vehicle, in accordance withembodiments;

FIG. 10 illustrates a movable object including a carrier and a payload,in accordance with embodiments; and

FIG. 11 is a schematic illustration by way of block diagram of a systemfor controlling a movable object, in accordance with embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure provides improved systems, methods, and devicesfor controlling a payload. In some embodiments, a payload is coupled toanother device (e.g., a movable object such as a UAV) using a carrierthat controls the position and/or orientation (attitude) of the payload.For instance, an instruction regarding a desired movement of the payloadcan be received (e.g., from a user and/or from a processor onboard themovable object) and a corresponding movement of the carrier to achievethe desired movement of the payload can be determined. Advantageously,the embodiments herein can account for external disturbances on thecarrier as well as the specific motion characteristics of the carrierwhen determining the appropriate carrier movement, thus enhancing therobustness of the system to external disturbances and improving theaccuracy of payload control.

As described herein, an external disturbance may include any movements,forces, and/or torques applied to the carrier and/or payload from asource external to the payload and carrier. For instance, externaldisturbances may be produced by the movable object connected to thepayload and carrier, another movable object, environmental conditions(e.g., wind, precipitation), temperature changes, obstacles within theenvironment, or combinations thereof.

Although some embodiments herein are presented in the context of UAVs,it shall be understood that the present disclosure can be applied toother types of movable objects, such as ground vehicles. Examples ofmovable objects suitable for use with the systems, methods, and devicesprovided herein are described in further detail below.

The movable objects described herein can be operated completelyautonomously (e.g., by a suitable computing system such as an onboardcontroller), semi-autonomously, or manually (e.g., by a human user). Themovable object can receive commands from a suitable entity (e.g., humanuser or autonomous control system) and respond to such commands byperforming one or more actions. For example, the movable object can be aUAV controlled to take off from the ground, move within the air (e.g.,with up to three degrees of freedom in translation and up to threedegrees of freedom in rotation), move to target location or to asequence of target locations, hover within the air, land on the ground,and so on. As another example, the movable object can be controlled tomove at a specified velocity and/or acceleration (e.g., with up to threedegrees of freedom in translation and up to three degrees of freedom inrotation) or along a specified movement path. Furthermore, the commandscan be used to control one or more components, such as the componentsdescribed herein (e.g., sensors, actuators, propulsion units, payload,etc.). For instance, some commands can be used to control the position,orientation, and/or operation of a payload such as a camera.

In some embodiments, the movable object is configured to carry apayload. The payload can include one or more of passengers, cargo,equipment, instruments, and the like. The payload can be provided withina housing. The housing may be separate from a housing of the movableobject, or be part of a housing for a movable object. Alternatively, thepayload can be provided with a housing while the movable object does nothave a housing. Alternatively, portions of the payload or the entirepayload can be provided without a housing. The payload can be rigidlyfixed relative to the movable object. Optionally, the payload can bemovable relative to the movable object (e.g., translatable or rotatablerelative to the movable object).

In some embodiments, the payload can be configured not to perform anyoperation or function. Alternatively, the payload can be a payloadconfigured to perform an operation or function, also known as afunctional payload. For example, the payload can include one or moresensors for surveying one or more targets. Any suitable sensor can beincorporated into the payload, such as an image capture device (e.g., acamera), an audio capture device (e.g., a parabolic microphone), aninfrared imaging device, or an ultraviolet imaging device. The sensorcan provide static sensing data (e.g., a photograph) or dynamic sensingdata (e.g., a video). In some embodiments, the sensor provides sensingdata for the target of the payload. Alternatively or in combination, thepayload can include one or more emitters for providing signals to one ormore targets. Any suitable emitter can be used, such as an illuminationsource or a sound source. In some embodiments, the payload includes oneor more transceivers, such as for communication with a module remotefrom the movable object. Optionally, the payload can be configured tointeract with the environment or a target. For example, the payload caninclude a tool, instrument, or mechanism capable of manipulatingobjects, such as a robotic arm.

In some embodiments, the movable object is coupled to a carrier for thepayload. The carrier can be provided for the payload and the payload canbe coupled to the movable object via the carrier, either directly (e.g.,directly contacting the movable object) or indirectly (e.g., notcontacting the movable object). Conversely, the payload can be mountedon the movable object without requiring a carrier. The payload can beintegrally formed with the carrier. Alternatively, the payload can bereleasably coupled to the carrier. In some embodiments, the payload caninclude one or more payload elements, and one or more of the payloadelements can be movable relative to the movable object and/or thecarrier, as described above.

The carrier can be integrally formed with the movable object.Alternatively, the carrier can be releasably coupled to the movableobject. The carrier can be coupled to the movable object directly orindirectly. The carrier can provide support to the payload (e.g., carryat least part of the weight of the payload). The carrier can be asuitable mounting structure (e.g., a gimbal platform) capable ofstabilizing and/or directing the movement of the payload. In someembodiments, the carrier can be adapted to control the state of thepayload (e.g., position and/or orientation) relative to the movableobject. The carrier can be rotatably coupled to the movable object(e.g., via a rotatable joint or connection) so as to rotate relative tothe movable object about one or more rotational axes. For example, thecarrier can be configured to move relative to the movable object (e.g.,with respect to one, two, or three degrees of translation and/or one,two, or three degrees of rotation) such that the payload maintains itsposition and/or orientation relative to a suitable reference frameregardless of the movement of the movable object. The reference framecan be a fixed reference frame (e.g., the surrounding environment).Alternatively, the reference frame can be a moving reference frame(e.g., the movable object, a payload target).

In some embodiments, the carrier can be configured to permit movement ofthe payload relative to the carrier and/or movable object. The movementcan be a translation with respect to up to three degrees of freedom(e.g., along one, two, or three axes) or a rotation with respect to upto three degrees of freedom (e.g., about one, two, or three axes), orany suitable combination thereof. In some embodiments, some or all ofthe axes of movement are orthogonal axes, e.g., a roll, pitch, and yawaxis. For example, the carrier can be configured to permit movement ofthe payload about a roll, pitch, and/or yaw axis. In some embodiments,the carrier is a single-axis or multi-axis gimbal that permits movementof the payload about a roll, pitch, and/or yaw axis. In alternativeembodiments, some or all of the axes of movement may be non-orthogonalaxes.

In some embodiments, the carrier includes one or more frames thatprovide support to the payload, such as one, two, three, or more frames.For instance, the carrier can include a single frame that is coupled(e.g., rotatably coupled) to the movable object and the payload. Thecarrier can include a first frame that is coupled (e.g., rotatablycoupled) to the payload and a second frame that is coupled (e.g.,rotatably coupled) to the movable object, and the first and secondframes can be coupled (e.g., rotatably coupled) to each other, such thatthe payload is serially coupled to the movable object by the first frameand second frame. The carrier can include a first frame that is coupled(e.g., rotatably coupled) to the payload, a second frame that is coupled(e.g., rotatably coupled) to the movable object, and a third framecoupling (e.g., rotatably coupling) the first and second frames, suchthat the payload is serially coupled to the movable object by the first,third, and second frames. In some embodiments, a frame coupled to themovable object may be referred to as an “outer” or “outermost” frame, aframe coupled to the payload may be referred to as an “inner” or“innermost” frame, and a frame that is not directly coupled to themovable object or the payload may be referred to as a “middle frame.”

Some or all of the frames can be movable relative to one another, andthe carrier can include one or more actuators (e.g., motors) thatactuate movement of the individual carrier frames. For instance, anactuator can actuate rotation of a carrier frame by applying a torque tothe carrier frame about an axis of rotation. The actuators can permitthe movement of multiple frames simultaneously, or may be configured topermit the movement of a single frame at a time. The movement of theframes can produce a corresponding movement of the payload. For example,the actuators can actuate a rotation of one or more frames about one ormore axes of rotation (e.g., roll axis, pitch axis, or yaw axis). Therotation of the one or more frames can cause a payload to rotate aboutone or more axes of rotation relative to the movable object.Alternatively or in combination, the carrier actuation assembly canactuate a translation of frames along one or more axes of translation,and thereby produce a translation of the payload along one or morecorresponding axes relative to the movable object. In some embodiments,the carrier includes one or more of: a yaw frame and a yaw actuatorcoupled to the yaw frame so as to actuate rotation of the yaw frameabout a yaw axis; a roll frame and a roll actuator configured to actuaterotation of the roll frame about a roll axis; and/or a pitch frame and apitch actuator configured to actuate rotation of the pitch frame about apitch axis. In some embodiments, the carrier is coupled to the movableobject via the yaw frame, while in other embodiments, the carrier can becoupled to the movable object via the pitch or roll frame.

In some embodiments, the carrier is directly coupled to the movableobject. In other embodiments, the carrier is coupled to the movableobject via a damping element. The damping element can be any elementsuitable for damping motion of the carrier and/or payload, such as anactive damping element, a passive damping element, or a hybrid dampingelement having both active and passive damping characteristics. Thedamping element can be configured to reduce unwanted motions (e.g.,vibrations, external disturbances) of the carrier and/or payload. Themotion damped by the damping elements provided herein can include one ormore of vibrations, oscillations, shaking, or impacts. Such motions mayresult from movement of the movable object, environmental conditions(e.g., wind, snow, rain), and/or collisions with other objects, forexample. Such motions may originate from motions of the movable objectthat are transmitted to the payload via the carrier. The damping elementmay provide motion damping by isolating the carrier and/or payload fromthe source of unwanted motion by dissipating or reducing the amount ofmotion transmitted to carrier and/or payload (e.g., vibrationisolation). The damping element may reduce the magnitude (e.g.,amplitude) of the motion that would otherwise be experienced by thecarrier and/or payload, such as by greater than or equal toapproximately 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%. Insome instances, the damping element can be configured to reduce motionshaving certain frequencies. For example, some damping elements canreduce high frequency motions, while other damping elements can reducelow frequency motions. A damping element can damp motions havingfrequencies greater than or equal to about 0.5 Hz, 1 Hz, 5 Hz, 10 Hz, 20Hz, 30 Hz, 40 Hz, 50 Hz, 100 Hz, 200 Hz, 300 Hz, 400 Hz, 500 Hz, 600 Hz,700 Hz, 800 Hz, 900 Hz, or 1000 Hz. Alternatively, a damping elementdamp motions having frequencies less than or equal to about 0.5 Hz, 1Hz, 5 Hz, 10 Hz, 20 Hz, 30 Hz, 40 Hz, 50 Hz, 100 Hz, 200 Hz, 300 Hz, 400Hz, 500 Hz, 600 Hz, 700 Hz, 800 Hz, 900 Hz, or 1000 Hz.

The damping elements described herein can be formed from any suitablematerial or combination of materials, including solid, liquid, orgaseous materials. The materials used for the damping elements may becompressible and/or deformable. For example, the damping element can bea sponge, foam, rubber material, gel, and the like. Alternatively or inaddition, the damping element can include piezoelectric materials orshape memory materials. The damping element can include one or moremechanical elements, such as springs, pistons, hydraulics, pneumatics,dashpots, shock absorbers, isolators, and the like. The properties ofthe damping element can be selected so as to provide a predeterminedamount of motion damping. For example, the damping element may have acharacteristic stiffness, which may correspond to a Young's modulus ofthe damping element. The Young's modulus may be greater than or equal toapproximately 0.01 GPa, 0.05 GPa, 0.1 GPa, 0.2 GPa, 0.3 GPa, 0.4 GPa,0.5 GPa, 0.6 GPa, 0.7 GPa, 0.8 GPa, 0.9 GPa, 1 GPa, or 5 GPa.Alternatively, the Young's modulus may be less than or equal toapproximately 0.01 GPa, 0.05 GPa, 0.1 GPa, 0.2 GPa, 0.3 GPa, 0.4 GPa,0.5 GPa, 0.6 GPa, 0.7 GPa, 0.8 GPa, 0.9 GPa, 1 GPa, or 5 GPa. In someinstances, the damping element may have viscoelastic properties. Theproperties of the damping element may be isotropic or anisotropic. Forinstance, the damping element may provide motion damping equally alongall directions of motion. Conversely, the damping element may providemotion damping only along a subset of the directions of motion (e.g.,along a single direction of motion).

FIG. 1 illustrates a movable object 100, carrier 102, and payload 104,in accordance with embodiments. Although the movable object 100 isdepicted as a UAV and the payload 104 is depicted as an imaging device,it shall be understood that other types of movable objects and payloadscan be used in alternative embodiments. Additionally, although thecarrier 102 and payload 104 are depicted as being located underneath themovable object 100, it shall be appreciated that other locations for thecarrier 102 and payload 104 are also possible, e.g., above or to theside of the movable object 100.

In the embodiment of FIG. 1, the movable object 100 supports the carrier102 and payload 104, and the carrier 102 is used to control the movementof the payload 104 relative to the movable object 100 (e.g., rotationabout a roll, pitch, and/or yaw axis). The carrier 102 can beelectrically coupled to one or more components of the movable object 100(e.g., a processor within the movable object 100) so as to receiveinstructions for the movement of the carrier 102 or components thereofand/or transmit data regarding the current state (e.g., position and/ororientation) of the carrier 102 or components thereof. Optionally, thepayload 104 can be electrically coupled to one or more components of themovable object 100 (e.g., a processor within the movable object 100) soas to receive instructions for the operation of the payload 104 orcomponents thereof, transmit data regarding the current state (e.g.,position, orientation, operating state, etc.) of the payload 104 orcomponents thereof, and/or transmit data generated by the payload 104(e.g., image data generated an the imaging device). The payload 104 canbe electrically coupled to the movable object 100 via electricalconnections coupled to or contained within the carrier 102, or can beelectrically coupled to the movable object 100 independently of thecarrier 102 (e.g., via wireless communication).

Optionally, the carrier 102 can be coupled to the movable object 100 viaa damping element 106. In the depicted embodiment, the damping element106 includes a plurality of rubber damping balls 108 (e.g., four rubberdamping balls). However, it shall be appreciated that other types ofdamping elements can also be used in combination with or alternativelyto the damping element 106. The carrier 102 can be coupled to thedamping element 106 via a first coupling structure 110, depicted hereinas a rigid plate, while the movable object 100 is coupled to the dampingelement 106 via a second coupling structure 112, also depicted as arigid plate. Thus, it can be seen that the damping balls 108 can reducethe amount of motion transmitted from the movable object 100 to thecarrier 102 and payload 104.

FIG. 2 illustrates an apparatus 200 for controlling a payload 202 (e.g.,an imaging device), in accordance with embodiments. The elements of theapparatus 200 can be used in combination with any of the systems,devices, and methods described herein. The apparatus 200 can be carriedby a movable object (not shown), such as a UAV. The apparatus 200includes a carrier 204 which is coupled to the payload 202. In thedepicted embodiment, the carrier 204 includes a first frame 206 affixedto the payload 202 and a second frame 208 coupled to the first frame206. The second frame 208 can be coupled to the movable object via adamping element 210. The damping element 210 can include a plurality ofrubber damping balls 212 (e.g., four rubber damping balls), and thecarrier 204 can be coupled to the damping element 210 via a couplingstructure 214 (e.g., a plate). The damping element 210 can be configuredto absorb and/or reduce vibrations transmitted to the carrier 204 andpayload 202 from the movable object.

In the depicted embodiment, the second frame 208 is a yaw frame that isactuated by a yaw actuator 216 in order to rotate the carrier 204 andcoupled payload 202 about a yaw axis, and the first frame 206 is a rollframe that is actuated by a roll actuator 218 in order to rotate thecarrier 204 and coupled payload 202 about a roll axis. The carrier 204can also include a pitch actuator 220 configured to rotate the payload202 about a pitch axis. The actuators 216, 218, and 220 can each apply atorque to rotate the respective frame or payload about the correspondingaxis of rotation. Each actuator can be a motor including a rotor and astator. For instance, the yaw actuator 216 can include a rotor coupledto the yaw frame (second frame 208) and a stator coupled to the movableobject (not shown), or vice-versa. However, it shall be appreciated thatalternative configurations of the carrier can also be used (e.g., lessthan or more than two frames, the second frame 208 may be a pitch frameor a roll frame rather than a yaw frame, the first frame may be a yawframe or a pitch frame rather than a roll frame, a separate pitch framecan be provided to coupled rotate the payload about a pitch axis, etc.).

As discussed above and herein, the carrier can be used to control thespatial disposition (e.g., position and/or orientation) of a coupledpayload. For instance, the carrier can be used to move (e.g., translateand/or rotate) the payload to a desired spatial disposition. The desiredspatial disposition can be manually input by a user (e.g., via remoteterminal or other external device in communication with the movableobject, carrier, and/or payload), determined autonomously withoutrequiring user input (e.g., by one or more processors of the movableobject, carrier, and/or payload), or determined semi-autonomously withaid of one or more processors of the movable object, carrier, and/orpayload. The desired spatial disposition can be used to calculate amovement of the carrier or one or more components thereof (e.g., one ormore frames) that would achieve the desired spatial disposition of thepayload.

For example, in some embodiments, an input angle (e.g., a yaw angle)associated with a desired attitude of the payload is received by one ormore processors (e.g., of the movable object, carrier, and/or payload).Based on the input angle, the one or more processors can determine anoutput torque to be applied to the carrier or one or more componentsthereof (e.g., a yaw frame) in order to achieve the desired attitude.The output torque can be determined in a variety of ways, such as usinga feedback control loop. The feedback control loop can take the inputangle as an input and output the output torque as an output. Thefeedback control loop can be implemented using one or more of aproportional (P) controller, a proportional-derivative (PD) controller,a proportional-integral (PI) controller, aproportional-integral-derivative (PID) controller, or combinationsthereof.

FIG. 3 illustrates a block diagram of a feedback control loop 300 forcontrolling an attitude of a payload, in accordance with embodiments.The feedback loop 300 can include a processor 302 (e.g., a digitalsignal processor (DSP)), a payload sensor 304, an actuator 306 (e.g., amotor), and a frame 308. The processor 302 can be located on the movableobject, carrier, or payload. Alternatively, rather than using a singleprocessor 302, multiple processors can be used, each of which isindependently located on the movable object, carrier, or payload. Theframe 308 can be an outer frame of a carrier that is coupled to amovable object, such as a yaw frame, and the actuator 306 can be coupledto the frame 308 in order to rotate the frame 308 about an axis, such asa yaw axis.

The payload sensor(s) 304 can be any sensor suitable for obtaining dataindicative of a spatial disposition (e.g., position, orientation, angle)and/or motion characteristic (e.g., translational (linear) velocity,angular velocity, translational (linear) acceleration, angularacceleration) of a payload, such as an inertial sensor. An inertialsensor may be used herein to refer a motion sensor (e.g., a velocitysensor, an acceleration sensor such as an accelerometer), an orientationsensor (e.g., a gyroscope, inclinometer), or an IMU having one or moreintegrated motion sensors and/or one or more integrated orientationsensors. An inertial sensor may provide sensing data relative to asingle axis of motion. The axis of motion may correspond to an axis ofthe inertial sensor (e.g., a longitudinal axis). A plurality of inertialsensors can be used, with each inertial sensor providing measurementsalong a different axis of motion. For example, three accelerometers canbe used to provide acceleration data along three different axes ofmotion. The three directions of motion may be orthogonal axes. One ormore of the accelerometers may be linear accelerometers configured tomeasure acceleration along a translational axis. Conversely, one or moreof the accelerometers may be angular accelerometers configured tomeasure angular acceleration around a rotational axis. As anotherexample, three gyroscopes can be used to provide orientation data aboutthree different axes of rotation. The three axes of rotation may beorthogonal axes (e.g., roll axis, pitch axis, yaw axis). Alternatively,at least some or all of the inertial sensors may provide measurementrelative to the same axes of motion. Such redundancy may be implemented,for instance, to improve measurement accuracy. Optionally, a singleinertial sensor may be capable of providing sensing data relative to aplurality of axes. For example, an IMU including a plurality ofaccelerometers and gyroscopes can be used to generate acceleration dataand orientation data with respect to up to six axes of motion.Alternatively, a single accelerometer can be used to detect accelerationalong multiple axes, and a single gyroscope can be used to detectrotation about multiple axes.

The payload sensor(s) 304 can be carried by the payload. The payloadsensor can be situated on any suitable portion of the payload, such asabove, underneath, on the side(s) of, or within a body of the payload.In some embodiments, one or more sensors can be enclosed within ahousing of the payload, positioned outside the housing, coupled to asurface (e.g., inner or outer surface) of the housing, or can form partof the housing. Some sensors can be mechanically coupled to the payloadsuch that the spatial disposition and/or motion of the payloadcorrespond to the spatial disposition and/or motion of the sensors. Thesensor can be coupled to the payload via a rigid coupling, such that thesensor does not move relative to the portion of the payload to which itis attached. Alternatively, the coupling between the sensor and thepayload can permit movement of the sensor relative to the payload. Thecoupling can be a permanent coupling or non-permanent (e.g., releasable)coupling. Suitable coupling methods can include adhesives, bonding,welding, and/or fasteners (e.g., screws, nails, pins, etc.). In someembodiments, the coupling between the sensor and the payload comprisesshock absorbers or dampers that reduce vibrations or other undesirablemechanical movements from being transmitted from the payload body to thesensor. Optionally, the sensor can be integrally formed with a portionof the payload. Furthermore, the sensor can be electrically coupled witha portion of the payload (e.g., processing unit, control system, datastorage). In alternative embodiments, the payload sensor(s) 304 may notnecessarily be directly coupled to the payload, but may be connected toanother component that is directly coupled to the payload (e.g., aninner frame directly coupled to the payload).

The processor 302 can receive an input angle 310 associated with adesired attitude of the payload (e.g., a yaw angle). For instance, theinput angle 310 can be an angle of the frame 308 that would achieve thedesired attitude of the payload. The processor 302 can also receive acurrent angle 312 associated with a current or instantaneous attitude ofthe payload from one or more payload sensors 304. The current angle 312can be a current angle of the frame 308 corresponding to the currentattitude of the payload. In some embodiments, the one or more payloadsensors 304 output data indicative of an angle of the payload, and thecurrent angle 312 of the frame 308 can be calculated based on the angleof the payload and/or information regarding the angles of other payloadcomponents (e.g., other carrier frames). Optionally, a rotation matrixcan be used to convert the payload angle to the current angle 312.

The processor 302 can calculate the difference between the input angle310 and the current angle 312, also referred to as the “error” in theangle 314. The error in the angle 314 can be input into a first PDcontroller 316. The first PD controller 316 can be implemented accordingto methods known to those of skill in the art. The first PD controller316 can output an output angular velocity 318. The output angularvelocity 318 can correspond to an angular velocity at which the frame308 should be rotated in order to achieve the desired attitude of thepayload.

The processor 302 can calculate the difference between the outputangular velocity 318 and a current angular velocity 320 received fromthe payload sensor(s) 304, also known as the “error” in the angularvelocity 322. The current angular velocity 320 can be associated with acurrent or instantaneous angular velocity of the payload. For instance,the current angular velocity 320 can be a current angle of the frame 308corresponding to the current angular velocity of the payload. In someembodiments, the one or more payload sensors 304 output data indicativeof an angular velocity of the payload, and the current angular velocity320 of the frame 308 can be calculated based on the angular velocity ofthe payload and/or information regarding the angular velocities of otherpayload components (e.g., other carrier frames). Optionally, a rotationmatrix can be used to convert the payload angular velocity to thecurrent angular velocity 320.

The error in the angular velocity 322 can be input into a second PDcontroller 324. The second PD controller 324 can be implementedaccording to methods known to those of skill in the art. The second PDcontroller 324 can output an output torque 326. The output torque 326can correspond to a torque which should be applied to the frame 308 inorder to achieve the desired attitude of the payload. The processor 302can transmit instructions to the actuator 306 to cause the actuator 306to apply the output torque 326 to the frame 308.

In some embodiments, an external disturbance to the carrier may resultin a disturbance torque 328 being applied to the frame 308, such thatthe actual amount of torque applied to the frame 308 may be the sum ofthe output torque 326 applied by the actuator 306 and the disturbancetorque 328. Thus, it can be seen that the additional disturbance torque328 may cause the angle that is actually achieved by the frame 308 to bedifferent from the input angle 310, which in turn may result in theactual attitude of the payload differing from the desired attitude.These discrepancies may be detrimental to accurate control of payloadattitude.

In some embodiments, the systems, methods, and devices of the presentdisclosure address these issues by determining an estimated disturbancetorque that would be applied to the carrier by an external disturbance,and adjusting the output torque to be applied to the carrier based onthe estimated disturbance torque. The embodiments herein can utilize oneor more external disturbance sensors directly or indirectly coupled tothe carrier in order to obtain data indicative of the externaldisturbance experienced by the carrier, such as spatial disposition(e.g., position, orientation, angle) and/or motion characteristics ofthe carrier (e.g., translational velocity, angular velocity,translational acceleration, angular acceleration). The one or moresensors can include one or more inertial sensors. As previouslydiscussed, an inertial sensor may include a motion sensor (e.g., avelocity sensor, an acceleration sensor such as an accelerometer), anorientation sensor (e.g., a gyroscope, inclinometer), or an IMU havingone or more integrated motion sensors and/or one or more integratedorientation sensors.

In some embodiments, the external disturbance sensor(s) are located onthe carrier. The sensor(s) can be situated on any suitable portion ofthe carrier, such as above, underneath, on the side(s) of, or within aportion of the carrier. In some embodiments, one or more sensors can beenclosed within a frame of the carrier, positioned outside the frame,coupled to a surface (e.g., inner or outer surface) of the frame, or canform part of the frame. In some embodiments, one or more sensors can beenclosed within an actuator of the carrier, positioned outside theactuator, coupled to a surface (e.g., inner or outer surface) of theactuator, or can form part of the actuator. In some embodiments, one ormore sensors are located on the carrier along an axis of rotation of thecarrier. For instance, a sensor may be coupled to a yaw frame or a yawactuator at a location along the yaw axis of the yaw frame.

Some sensors can be mechanically coupled to the carrier such that thespatial disposition and/or motion of the carrier correspond to thespatial disposition and/or motion of the sensors. The sensor can becoupled to the carrier via a rigid coupling, such that the sensor doesnot move relative to the portion of the carrier to which it is attached.Alternatively, the coupling between the sensor and the carrier canpermit movement of the sensor relative to the carrier. The coupling canbe a permanent coupling or non-permanent (e.g., releasable) coupling.Suitable coupling methods can include adhesives, bonding, welding,and/or fasteners (e.g., screws, nails, pins, etc.). In some embodiments,the coupling between the sensor and the carrier comprises shockabsorbers or dampers that reduce vibrations or other undesirablemechanical movements from being transmitted from the carrier to thesensor. Optionally, the sensor can be integrally formed with a portionof the carrier. Furthermore, the sensor can be electrically coupled witha portion of the carrier (e.g., processing unit, control system, datastorage).

In alternative embodiments, the sensor(s) may not necessarily bedirectly coupled to the carrier, but may be connected to anothercomponent that is directly coupled to the carrier, such as a dampingelement or a coupling structure connecting the carrier to the dampingelement. As discussed above and herein, the damping element may beinterposed between the carrier and a movable object so as to reducetransmission of unwanted motions from the movable object to the carrier.A coupling structure may be used to connect the carrier or a portionthereof (e.g., a frame of the carrier) to the damping element. The oneor more sensors can be located on the damping element and/or couplingstructure so as to provide data regarding any external disturbancesexperienced by the carrier.

The sensor data obtained by the external disturbance sensor(s) can beprocessed in order to estimate the amount of external disturbancetorque. In some embodiments, the sensor data is input into a dynamicmodel of carrier and/or payload, and the output of the model is theestimated external disturbance torque. The dynamic model can includeparameters corresponding to the specific characteristics of theparticular carrier and/or payload. The determination of model parametersand generation of the dynamic model can be determined according tomethods known to those of skill in the art. The dynamic model can bedetermined prior to operation and can be pre-stored in memory located onthe payload, carrier, and/or movable object.

In some embodiments, for a three-axis carrier or gimbal, themathematical model for the relation between the external disturbancetorque on the outer frame (e.g., the yaw frame) and the acceleration ofthe damping element connecting the carrier to the movable object is:T _(disturb)=(K ₁ sin(Ψ)+K ₂ cos(θ)cos(Ψ))a _(x)+(K ₃ cos(Ψ)+K ₄cos(θ)sin(Ψ)a _(y)

where: T_(disturb) is an estimation of the amount of disturbance torqueon the actuator of the outer frame (e.g., the yaw actuator); K₁, K₂, K₃,and K₄ are parameters of the dynamic model, which are determined basedon the weight, rotational inertial tensor, and geometry of the threecarrier frames; a_(x) and a_(y) are the acceleration measurements ofdamping element in x and y directions, respectively; and Ψ, θ are thecurrent joint angles as measured by sensors (e.g., potentiometers)coupled to the actuators of the carrier frames (e.g., Ψ is the angle ofthe yaw actuator of the yaw frame, and θ is the angle of the rollactuator of the roll frame).

FIG. 4 illustrates an apparatus 400 for controlling a payload 402 (e.g.,an imaging device) in accordance with embodiments. The elements of theapparatus 400 can be used in combination with any of the systems,devices, and methods described herein. The apparatus 400 can be carriedby a movable object (not shown), such as a UAV. Similar to the apparatus200 of FIG. 2, the apparatus 400 includes a carrier 404 coupled to thepayload 402, the carrier 404 including a first frame 406 affixed to thepayload 402 and a second frame 408 coupled to the first frame 406. Inthe depicted embodiment, the second frame 408 is actuated by an actuator410 in order to rotate the carrier 404 and coupled payload 402 about anaxis of rotation (e.g., a yaw axis). The actuator 410 can apply a torqueto rotate the frame about the corresponding axis of rotation. The secondframe 408 can be coupled to the movable object via a damping element(not shown), such as a plurality of rubber damping balls. The carrier404 can be coupled to the damping element via a coupling structure 412(e.g., a plate).

The apparatus 400 can include one or more external disturbance sensors414 coupled directly or indirectly to the second frame 408. The externaldisturbance sensor(s) 414 can be one or more accelerometers, one or moregyroscopes, or an IMU with one or more accelerometers and one or moregyroscopes. In the depicted embodiment, the external disturbancesensor(s) 414 are located on the coupling structure 412 connecting thesecond frame 408 to the damping element, such as on a printed circuitboard (PCB) or flexible printed circuit (FPC) 416 attached onto thecoupling structure 412. The sensor data is transmitted to one or moreprocessors (e.g., a DSP) via a FPC cable 418 and a FPC cable connector420. In some embodiments, the one or more processors are located in thepayload 402 and the FPC cable 418 extends through the first frame 406and second frame 408. In alternative embodiments, the one or moreprocessors may be located elsewhere (e.g., on the carrier 404 or movableobject) and the FPC cable 418 can be routed appropriately.

In alternative embodiments, the external disturbance sensor(s) 414 canbe located on other portions of the apparatus 400, such as on thecarrier 404. For example, one or more external disturbance sensor(s) 414can be positioned on or in proximity to the second frame 408.Alternatively or in combination, one or more external disturbancesensor(s) 414 can be positioned on or in proximity to the actuator 410.In embodiments where the sensor(s) 414 are located on the second frame408, the sensor data from the sensor(s) 414 can be converted from thereference frame of the second frame 408 to the reference frame of thecoupling structure 412, e.g., using a single rotation matrixtransformation.

In some embodiments, the one or more external disturbance sensor(s) 414are positioned so as to lie along the axis of rotation of the secondframe 408 (e.g., a yaw axis). In the embodiment of FIG. 4, the externaldisturbance sensor(s) 414 is illustrated as being positioned on thecoupling structure 412 at a location along the axis of rotation of thesecond frame 408. The sensor(s) 414 can also be positioned at otherlocations on the apparatus 400 that are along the axis of rotation ofthe second frame 408, such as underneath the actuator 410. In someembodiments, positioning the sensor(s) 414 along the axis of rotation ofthe second frame 408 can simplify the disturbance torque calculationsdescribed herein, since there may be no relative acceleration betweenthe coupling structure 412 and actuator 410 in the horizontal direction.

FIG. 5 illustrates a movable object 500, carrier 502, and payload 504,in accordance with embodiments. Although the movable object 500 isdepicted as a UAV and the payload 504 is depicted as an imaging device,it shall be understood that other types of movable objects and payloadscan be used in alternative embodiments. Additionally, although thecarrier 502 and payload 504 are depicted as being located underneath themovable object 500, it shall be appreciated that other locations for thecarrier 502 and payload 504 are also possible, e.g., above or to theside of the movable object 500.

Similar to the embodiment of FIG. 1, the movable object 500 supports thecarrier 502 and payload 504, and the carrier 502 is used to control themovement of the payload 504 relative to the movable object 500 (e.g.,rotation about a roll, pitch, and/or yaw axis). The carrier 502 can beelectrically coupled to one or more components of the movable object 500(e.g., a processor within the movable object 500) so as to receiveinstructions for the movement of the carrier 502 or components thereofand/or transmit data regarding the current state (e.g., position and/ororientation) of the carrier 502 or components thereof. Optionally, thepayload 504 can be electrically coupled to one or more components of themovable object 500 (e.g., a processor within the movable object 500) soas to receive instructions for the operation of the payload 504 orcomponents thereof, transmit data regarding the current state (e.g.,position, orientation, operating state, etc.) of the payload 504 orcomponents thereof, and/or transmit data generated by the payload 504(e.g., image data generated an the imaging device). The payload 504 canbe electrically coupled to the movable object 500 via electricalconnections coupled to or contained within the carrier 502, or can beelectrically coupled to the movable object 500 independently of thecarrier 502 (e.g., via wireless communication).

Optionally, the carrier 502 can be coupled to the movable object 500 viaa damping element located within an external housing 506 of the movableobject 500. For instance, the external housing 506 can define aninterior cavity within the movable object 500, and the damping elementcan be located within the interior cavity. The carrier 502 can becoupled to the movable object 500 via a lower housing section 508.

FIG. 6 illustrates an apparatus 600 for controlling a payload 602including an internal damping element 603. The elements of the apparatus600 can be used in combination with any of the systems, devices, andmethods described herein. The apparatus 600 can be carried by a movableobject (not shown), such as a UAV (e.g., the UAV 500 of FIG. 5). Similarto the apparatus 400 of FIG. 4, the apparatus 600 includes a carrier 604coupled to the payload 602, the carrier 604 including a first frame 606affixed to the payload 602, a second frame 608 coupled to the firstframe 606, and an actuator 610 that applies torque to the second frame608 in order to rotate the carrier 604 and coupled payload 602 about anaxis of rotation (e.g., a yaw axis). The second frame 608 can be coupledto the movable object via a damping element 603 (not shown), shown hereas a plurality of rubber damping balls 612. The carrier 604 can becoupled to the damping element 603 via a coupling structure 614 (e.g., aplate). The coupling structure 614 and damping element 603 can belocated within an interior cavity defined by an external housing of themovable object. For instance, the external housing can include a lowerhousing section 616 and the coupling structure 614 and damping element630 can be located within the interior cavity coupled to the lowerhousing section 616. The apparatus 600 can further include one or moreexternal disturbance sensors coupled directly or indirectly to thesecond frame 608, e.g., attached to a PCB or FCB on the couplingstructure 614 within the interior cavity of the movable object.

FIG. 7 illustrates a block diagram of a feedback control loop 700 forcontrolling an attitude of a payload, in accordance with embodiments.The feedback loop 700 can include a processor 702 (e.g., a digitalsignal processor (DSP)), a payload sensor 704, an actuator 706 (e.g., amotor), and a frame 708. The payload sensor 704, actuator 706, and frame708 may be substantially similar to the elements of the feedback controlloop 300 described above with respect to FIG. 3. The feedback loop 700can further include one or more external disturbance sensors 709configured to detect an external disturbance applied to the carrierand/or payload.

Similar to the processor 302 of FIG. 3, the processor 702 can receive aninput angle 710 associated with a desired attitude of the payload (e.g.,a yaw angle). For instance, the input angle 710 can be an angle of theframe 708 that would achieve the desired attitude of the payload. Theprocessor 702 can also receive a current angle 712 associated with acurrent attitude of the payload from one or more payload sensors 704.The current angle 712 can be a current or instantaneous angle of theframe 708 corresponding to the current attitude of the payload. In someembodiments, the one or more payload sensors 704 output data indicativeof an angle of the payload, and the current angle 712 of the frame 708can be calculated based on the angle of the payload and/or informationregarding the angles of other payload components (e.g., other carrierframes). Optionally, a rotation matrix can be used to convert thepayload angle to the current angle 712.

The processor 702 can calculate the difference between the input angle710 and the current angle 712, also referred to as the “error” in theangle 714. The error in the angle 714 can be input into a first PDcontroller 716. The first PD controller 716 can be implemented accordingto methods known to those of skill in the art. The first PD controller716 can output an output angular velocity 718. The output angularvelocity 718 can correspond to an angular velocity at which the frame708 should be rotated in order to achieve the desired attitude of thepayload.

The processor 702 can calculate the difference between the outputangular velocity 718 and a current angular velocity 720 received fromthe payload sensor(s) 704, also known as the “error” in the angularvelocity 722. The current angular velocity 720 can be associated with acurrent or instantaneous angular velocity of the payload. For instance,the current angular velocity 720 can be a current angle of the frame 708corresponding to the current angular velocity of the payload. In someembodiments, the one or more payload sensors 704 output data indicativeof an angular velocity of the payload, and the current angular velocity720 of the frame 708 can be calculated based on the angular velocity ofthe payload and/or information regarding the angular velocities of otherpayload components (e.g., other carrier frames). Optionally, a rotationmatrix can be used to convert the payload angular velocity to thecurrent angular velocity 720.

The error in the angular velocity 722 can be input into a second PDcontroller 724. The second PD controller 724 can be implementedaccording to methods known to those of skill in the art. The second PDcontroller 724 can output an input torque 726.

In some embodiments, an external disturbance to the carrier may resultin a disturbance torque 728 being applied to the frame 708. The externaldisturbance sensor(s) 709 can provide measurement data indicative of anacceleration 730 (e.g., translational and/or angular acceleration) of adamping element coupling the frame 708 to the movable object. Theacceleration 730 can be input into a dynamic model 732 of the carrierimplemented by the processor 702. As described above and herein, thedynamic model 732 can include pre-stored parameters corresponding to theparticular characteristics of the carrier. The dynamic model 732 canoutput an estimated disturbance torque 734. The estimated disturbancetorque 734 can represent an estimated torque that would be applied onthe frame 708 as a result of the external disturbance. Optionally, theestimated disturbance torque 734 can be input into a third PD controller736 of the processor 702 in order to produce a refined disturbancetorque 738.

The processor 702 can calculate the difference between the input torque726 and refined disturbance torque 738 (or estimated disturbance torque734) in order to obtain an output torque 740. The output torque 740 cancorrespond to a torque which should be applied to the frame 708 in orderto achieve the desired attitude of the payload even when an externaldisturbance resulting in external disturbance torque 728 is present. Theprocessor 702 can transmit instructions to the actuator 706 to cause theactuator 706 to apply the output torque 740 to the frame 708.

FIG. 8 illustrates a method 800 for controlling a payload, in accordancewith embodiments. The method 800 can be performed using any embodimentof the systems and devices described herein. In some embodiments, themethod 800 can be performed using one or more processors of a motioncontroller, e.g., located on a movable object, carrier, and/or payload.The motion controller can be configured to effect movement of thecarrier to achieve a desired attitude of the payload.

In step 810, an input torque is determined based on an input angle andone or more motion characteristics of a payload. The input angle can beassociated with a desired attitude of the payload. The input angle canbe provided by a user using an external device in communication with thepayload. The input angle can be provided to one or more processors of amotion controller, e.g., on the payload, carrier, or movable object. Themotion characteristics of the payload can include a an instantaneousattitude, an instantaneous position, a linear velocity, an angularvelocity, a linear acceleration, and/or an angular acceleration of thepayload, and can be measured using one or more sensors located on or inproximity to the payload.

In some embodiments, the input torque is determined using a feedbackcontrol loop, such as the control loop depicted in FIG. 3 or FIG. 7. Thefeedback control loop can be implemented using at least one PDcontroller, e.g., a first PD controller configured to calculate an inputangular velocity based on a difference between an instantaneous anglemeasured by one or more sensors on the payload and the input angleand/or a second PD controller configured to calculate the input torquebased on a difference between an instantaneous angular velocity measuredby the one or more sensors on the payload and the input angularvelocity.

In step 820, an estimated disturbance torque is determined based on oneor more motion characteristics of a carrier to which the payload iscoupled. The estimated disturbance torque can be associated with adisturbance to the carrier. The disturbance can include one or more ofwind effects, temperature changes, or external impact to the payload orcarrier, for example. The motion characteristics of the carrier caninclude an instantaneous attitude, an instantaneous position, a linearvelocity, an angular velocity, a linear acceleration, and/or an angularacceleration of the carrier. The estimated disturbance torque can becalculated with respect to a rotatable joint on a frame of the carrier(e.g., a yaw frame), the rotatable joint being configured to couple theframe to the movable object.

In some embodiments, the carrier includes a first and second frame asdescribed herein, and the motion characteristics include at least alinear acceleration or an angular acceleration of the second frame. Asdiscussed above and herein, the motion characteristics can be measuredusing one or more sensors (e.g., inertial sensors) located at anysuitable location (e.g., on a frame of the carrier, such as on or inproximity to the second frame). In some embodiments, the sensors areconfigured to measure the motion characteristics of the carrier (e.g., asecond frame of the carrier) when coupled to the movable object via adamping element, and the sensors can be directly disposed on a couplingstructure connecting the damping element to the second frame. Theestimated disturbance torque can be determined based on one or moremotion characteristics of the carrier (e.g., linear acceleration orangular acceleration) measured using one or more sensors disposed on orin proximity to the carrier. Alternatively or in combination, theestimated disturbance torque can be determined based on one or moremotion characteristics of the damping element (e.g., linear accelerationor angular acceleration) measured using one or more sensors disposed onthe damping element. The motion characteristics of the damping elementcan be associated with the one or more motion characteristics of thecarrier (e.g., a second frame of the carrier).

The estimated disturbance torque can be determined in various ways. Insome embodiments, the estimated disturbance torque is determined by arotation matrix transformation comprising measurements of the one ormore motion characteristics of the carrier. Alternatively or incombination, the estimated disturbance torque is determined by inputtingone or more motion characteristics of a damping element into apredefined dynamics-based model of the carrier. In some embodiments, theestimated disturbance torque is further refined using a PD controller,e.g., by applying one or more filters to the estimated disturbancetorque.

In step 830, an output torque is calculated based on the input torqueand the estimated disturbance torque e.g., by one or more processors ofthe motion controller. The output torque can be calculated bycompensating the input torque with the estimated disturbance torque. Forinstance, the output torque can be calculated by subtracting theestimated disturbance torque from the input torque. In some embodiments,the output torque is calculated based on the input torque and therefined disturbance torque described above.

The output torque can be used to effect movement of the carrier toachieve the desired attitude of the payload. For instance, the motioncontroller can be configured to control an actuator that is coupled tothe carrier to rotate at the output torque so as to effect the movementof the carrier to achieve the desired attitude of the payload. Theactuator can be coupled to the second frame of the carrier, for example.In some embodiments, the output torque can be used in conjunction withan actual disturbance torque from the disturbance to effect the movementof the carrier so as to achieve the desired attitude of the payload. Theactual disturbance torque may be applied to a frame of the carrier, forexample.

The systems, devices, and methods described herein can be applied to awide variety of movable objects. As previously mentioned, anydescription herein of an aerial vehicle may apply to and be used for anymovable object. A movable object of the present disclosure can beconfigured to move within any suitable environment, such as in air(e.g., a fixed-wing, aircraft, a rotary-wing aircraft, or an aircrafthaving neither fixed wings nor rotary wings), in water (e.g., a ship ora submarine), on ground (e.g., a motor vehicle, such as a car, truck,bus, van, motorcycle; a movable structure or frame such as a stick,fishing pole; or a train), under the ground (e.g., a subway), in space(e.g., a spaceplane, a satellite, or a probe), or any combination ofthese environments. The movable object can be a vehicle, such as avehicle described elsewhere herein. In some embodiments, the movableobject can be mounted on a living subject, such as a human or an animal.Suitable animals can include avines, canines, felines, equines, bovines,ovines, porcines, delphines, rodents, or insects.

The movable object may be capable of moving freely within theenvironment with respect to six degrees of freedom (e.g., three degreesof freedom in translation and three degrees of freedom in rotation).Alternatively, the movement of the movable object can be constrainedwith respect to one or more degrees of freedom, such as by apredetermined path, track, or orientation. The movement can be actuatedby any suitable actuation mechanism, such as an engine or a motor. Theactuation mechanism of the movable object can be powered by any suitableenergy source, such as electrical energy, magnetic energy, solar energy,wind energy, gravitational energy, chemical energy, nuclear energy, orany suitable combination thereof. The movable object may beself-propelled via a propulsion system, as described elsewhere herein.The propulsion system may optionally run on an energy source, such aselectrical energy, magnetic energy, solar energy, wind energy,gravitational energy, chemical energy, nuclear energy, or any suitablecombination thereof. Alternatively, the movable object may be carried bya living being.

In some instances, the movable object can be a vehicle. Suitablevehicles may include water vehicles, aerial vehicles, space vehicles, orground vehicles. For example, aerial vehicles may be fixed-wing aircraft(e.g., airplane, gliders), rotary-wing aircraft (e.g., helicopters,rotorcraft), aircraft having both fixed wings and rotary wings, oraircraft having neither (e.g., blimps, hot air balloons). A vehicle canbe self-propelled, such as self-propelled through the air, on or inwater, in space, or on or under the ground. A self-propelled vehicle canutilize a propulsion system, such as a propulsion system including oneor more engines, motors, wheels, axles, magnets, rotors, propellers,blades, nozzles, or any suitable combination thereof. In some instances,the propulsion system can be used to enable the movable object to takeoff from a surface, land on a surface, maintain its current positionand/or orientation (e.g., hover), change orientation, and/or changeposition.

The movable object can be controlled remotely by a user or controlledlocally by an occupant within or on the movable object. In someembodiments, the movable object s an unmanned movable object, such as aUAV. An unmanned movable object, such as a UAV, may not have an occupantonboard the movable object. The movable object can be controlled by ahuman or an autonomous control system (e.g., a computer control system),or any suitable combination thereof. The movable object can be anautonomous or semi-autonomous robot, such as a robot configured with anartificial intelligence.

The movable object can have any suitable size and/or dimensions. In someembodiments, the movable object may be of a size and/or dimensions tohave a human occupant within or on the vehicle. Alternatively, themovable object may be of size and/or dimensions smaller than thatcapable of having a human occupant within or on the vehicle. The movableobject may be of a size and/or dimensions suitable for being lifted orcarried by a human. Alternatively, the movable object may be larger thana size and/or dimensions suitable for being lifted or carried by ahuman. In some instances, the movable object may have a maximumdimension (e.g., length, width, height, diameter, diagonal) of less thanor equal to about: 2 cm, 5 cm, 10 cm, 50 cm, 1 m, 2 m, 5 m, or 10 m. Themaximum dimension may be greater than or equal to about: 2 cm, 5 cm, 10cm, 50 cm, 1 m, 2 m, 5 m, or 10 m. For example, the distance betweenshafts of opposite rotors of the movable object may be less than orequal to about: 2 cm, 5 cm, 10 cm, 50 cm, 1 m, 2 m, 5 m, or 10 m.Alternatively, the distance between shafts of opposite rotors may begreater than or equal to about: 2 cm, 5 cm, 10 cm, 50 cm, 1 m, 2 m, 5 m,or 10 m.

In some embodiments, the movable object may have a volume of less than100 cm×100 cm×100 cm, less than 50 cm×50 cm×30 cm, or less than 5 cm×5cm×3 cm. The total volume of the movable object may be less than orequal to about: 1 cm³, 2 cm³, 5 cm³, 10 cm³, 20 cm³, 30 cm³, 40 cm³, 50cm³, 60 cm³, 70 cm³, 80 cm³, 90 cm³, 100 cm³, 150 cm³, 200 cm³, 300 cm³,500 cm³, 750 cm³, 1000 cm³, 5000 cm³, 10,000 cm³, 100,000 cm³, 1 m³, or10 m³. Conversely, the total volume of the movable object may be greaterthan or equal to about: 1 cm³, 2 cm³, 5 cm³, 10 cm³, 20 cm³, 30 cm³, 40cm³, 50 cm³, 60 cm³, 70 cm³, 80 cm³, 90 cm³, 100 cm³, 150 cm³, 200 cm³,300 cm³, 500 cm³, 750 cm³, 1000 cm³, 5000 cm³, 10,000 cm³, 100,000 cm³,1 m³, or 10 m³.

In some embodiments, the movable object may have a footprint (which mayrefer to the lateral cross-sectional area encompassed by the movableobject) less than or equal to about: 32,000 cm², 20,000 cm², 10,000 cm²,1,000 cm², 500 cm², 100 cm², 50 cm², 10 cm², or 5 cm². Conversely, thefootprint may be greater than or equal to about: 32,000 cm², 20,000 cm²,10,000 cm², 1,000 cm², 500 cm², 100 cm², 50 cm², 10 cm², or 5 cm².

In some instances, the movable object may weigh no more than 1000 kg.The weight of the movable object may be less than or equal to about:1000 kg, 750 kg, 500 kg, 200 kg, 150 kg, 100 kg, 80 kg, 70 kg, 60 kg, 50kg, 45 kg, 40 kg, 35 kg, 30 kg, 25 kg, 20 kg, 15 kg, 12 kg, 10 kg, 9 kg,8 kg, 7 kg, 6 kg, 5 kg, 4 kg, 3 kg, 2 kg, 1 kg, 0.5 kg, 0.1 kg, 0.05 kg,or 0.01 kg. Conversely, the weight may be greater than or equal toabout: 1000 kg, 750 kg, 500 kg, 200 kg, 150 kg, 100 kg, 80 kg, 70 kg, 60kg, 50 kg, 45 kg, 40 kg, 35 kg, 30 kg, 25 kg, 20 kg, 15 kg, 12 kg, 10kg, 9 kg, 8 kg, 7 kg, 6 kg, 5 kg, 4 kg, 3 kg, 2 kg, 1 kg, 0.5 kg, 0.1kg, 0.05 kg, or 0.01 kg.

In some embodiments, a movable object may be small relative to a loadcarried by the movable object. The load may include a payload and/or acarrier, as described in further detail below. In some examples, a ratioof a movable object weight to a load weight may be greater than, lessthan, or equal to about 1:1. In some instances, a ratio of a movableobject weight to a load weight may be greater than, less than, or equalto about 1:1. Optionally, a ratio of a carrier weight to a load weightmay be greater than, less than, or equal to about 1:1. When desired, theratio of an movable object weight to a load weight may be less than orequal to: 1:2, 1:3, 1:4, 1:5, 1:10, or even less. Conversely, the ratioof a movable object weight to a load weight can also be greater than orequal to: 2:1, 3:1, 4:1, 5:1, 10:1, or even greater.

In some embodiments, the movable object may have low energy consumption.For example, the movable object may use less than about: 5 W/h, 4 W/h, 3W/h, 2 W/h, 1 W/h, or less. In some instances, a carrier of the movableobject may have low energy consumption. For example, the carrier may useless than about: 5 W/h, 4 W/h, 3 W/h, 2 W/h, 1 W/h, or less. Optionally,a payload of the movable object may have low energy consumption, such asless than about: 5 W/h, 4 W/h, 3 W/h, 2 W/h, 1 W/h, or less.

FIG. 9 illustrates an unmanned aerial vehicle (UAV) 900, in accordancewith embodiments of the present disclosure. The UAV may be an example ofa movable object as described herein. The UAV 900 can include apropulsion system having four rotors 902, 904, 906, and 908. Any numberof rotors may be provided (e.g., one, two, three, four, five, six, ormore). The rotors, rotor assemblies, or other propulsion systems of theunmanned aerial vehicle may enable the unmanned aerial vehicle tohover/maintain position, change orientation, and/or change location. Thedistance between shafts of opposite rotors can be any suitable length910. For example, the length 910 can be less than or equal to 2 m, orless than equal to 5 m. In some embodiments, the length 910 can bewithin a range from 40 cm to 1 m, from 10 cm to 2 m, or from 5 cm to 5m. Any description herein of a UAV may apply to a movable object, suchas a movable object of a different type, and vice versa.

In some embodiments, the movement of the movable object, carrier, andpayload relative to a fixed reference frame (e.g., the surroundingenvironment) and/or to each other, can be controlled by a terminal. Theterminal can be a remote control device at a location distant from themovable object, carrier, and/or payload. The terminal can be disposed onor affixed to a support platform. Alternatively, the terminal can be ahandheld or wearable device. For example, the terminal can include asmartphone, tablet, laptop, computer, glasses, gloves, helmet,microphone, or suitable combinations thereof. The terminal can include auser interface, such as a keyboard, mouse, joystick, touchscreen, ordisplay. Any suitable user input can be used to interact with theterminal, such as manually entered commands, voice control, gesturecontrol, or position control (e.g., via a movement, location or tilt ofthe terminal).

The terminal can be used to control any suitable state of the movableobject, carrier, and/or payload. For example, the terminal can be usedto control the position and/or orientation of the movable object,carrier, and/or payload relative to a fixed reference from and/or toeach other. In some embodiments, the terminal can be used to controlindividual elements of the movable object, carrier, and/or payload, suchas the actuation assembly of the carrier, a sensor of the payload, or anemitter of the payload. The terminal can include a wirelesscommunication device adapted to communicate with one or more of themovable object, carrier, or payload.

The terminal can include a suitable display unit for viewing informationof the movable object, carrier, and/or payload. For example, theterminal can be configured to display information of the movable object,carrier, and/or payload with respect to position, translationalvelocity, translational acceleration, orientation, angular velocity,angular acceleration, or any suitable combinations thereof. In someembodiments, the terminal can display information provided by thepayload, such as data provided by a functional payload (e.g., imagesrecorded by a camera or other image capturing device).

Optionally, the same terminal may both control the movable object,carrier, and/or payload, or a state of the movable object, carrierand/or payload, as well as receive and/or display information from themovable object, carrier and/or payload. For example, a terminal maycontrol the positioning of the payload relative to an environment, whiledisplaying image data captured by the payload, or information about theposition of the payload. Alternatively, different terminals may be usedfor different functions. For example, a first terminal may controlmovement or a state of the movable object, carrier, and/or payload whilea second terminal ma receive and/or display information from the movableobject, carrier, and/or payload. For example, a first terminal may beused to control the positioning of the payload relative to anenvironment while a second terminal displays image data captured by thepayload. Various communication nodes may be utilized between a movableobject and an integrated terminal that both controls the movable objectand receives data, or between the movable object and multiple terminalsthat both control the movable object and receives data. For example, atleast two different communication modes may be formed between themovable object and the terminal that both controls the movable objectand receives data from the movable object.

FIG. 10 illustrates a movable object 1000 including a carrier 1002 and apayload 1004, in accordance with embodiments. Although the movableobject 1000 is depicted as an aircraft, this depiction is not intendedto be limiting, and any suitable type of movable object can be used, aspreviously described herein. One of skill in the art would appreciatethat any of the embodiments described herein in the context of aircraftsystems can be applied to any suitable movable object (e.g., an UAV). Insome instances, the payload 1004 may be provided on the movable object1000 without requiring the carrier 1002. The movable object 1000 mayinclude propulsion mechanisms 1006, a sensing system 1008, and acommunication system 1010.

The propulsion mechanisms 1006 can include one or more of rotors,propellers, blades, engines, motors, wheels, axles, magnets, or nozzles,as previously described. For example, the propulsion mechanisms 1006 maybe self-tightening rotors, rotor assemblies, or other rotary propulsionunits, as disclosed elsewhere herein. The movable object may have one ormore, two or more, three or more, or four or more propulsion mechanisms.The propulsion mechanisms may all be of the same type. Alternatively,one or more propulsion mechanisms can be different types of propulsionmechanisms. The propulsion mechanisms 1006 can be mounted on the movableobject 1000 using any suitable means, such as a support element (e.g., adrive shaft) as described elsewhere herein. The propulsion mechanisms1006 can be mounted on any suitable portion of the movable object 1000,such on the top, bottom, front, back, sides, or suitable combinationsthereof.

In some embodiments, the propulsion mechanisms 1006 can enable themovable object 1000 to take off vertically from a surface or landvertically on a surface without requiring any horizontal movement of themovable object 1000 (e.g., without traveling down a runway). Optionally,the propulsion mechanisms 1006 can be operable to permit the movableobject 1000 to hover in the air at a specified position and/ororientation. One or more of the propulsion mechanisms 1000 may becontrolled independently of the other propulsion mechanisms.Alternatively, the propulsion mechanisms 1000 can be configured to becontrolled simultaneously. For example, the movable object 1000 can havemultiple horizontally oriented rotors that can provide lift and/orthrust to the movable object. The multiple horizontally oriented rotorscan be actuated to provide vertical takeoff, vertical landing, andhovering capabilities to the movable object 1000. In some embodiments,one or more of the horizontally oriented rotors may spin in a clockwisedirection, while one or more of the horizontally rotors may spin in acounterclockwise direction. For example, the number of clockwise rotorsmay be equal to the number of counterclockwise rotors. The rotation rateof each of the horizontally oriented rotors can be varied independentlyin order to control the lift and/or thrust produced by each rotor, andthereby adjust the spatial disposition, velocity, and/or acceleration ofthe movable object 1000 (e.g., with respect to up to three degrees oftranslation and up to three degrees of rotation).

The sensing system 1008 can include one or more sensors that may sensethe spatial disposition, velocity, and/or acceleration of the movableobject 1000 (e.g., with respect to up to three degrees of translationand up to three degrees of rotation). The one or more sensors caninclude global positioning system (GPS) sensors, motion sensors,inertial sensors, proximity sensors, or image sensors. The sensing dataprovided by the sensing system 1008 can be used to control the spatialdisposition, velocity, and/or orientation of the movable object 1000(e.g., using a suitable processing unit and/or control module, asdescribed below). Alternatively, the sensing system 1008 can be used toprovide data regarding the environment surrounding the movable object,such as weather conditions, proximity to potential obstacles, locationof geographical features, location of manmade structures, and the like.

The communication system 1010 enables communication with terminal 1012having a communication system 1014 via wireless signals 1016. Thecommunication systems 1010, 1014 may include any number of transmitters,receivers, and/or transceivers suitable for wireless communication. Thecommunication may be one-way communication, such that data can betransmitted in only one direction. For example, one-way communicationmay involve only the movable object 1000 transmitting data to theterminal 1012, or vice-versa. The data may be transmitted from one ormore transmitters of the communication system 1010 to one or morereceivers of the communication system 1012, or vice-versa.Alternatively, the communication may be two-way communication, such thatdata can be transmitted in both directions between the movable object1000 and the terminal 1012. The two-way communication can involvetransmitting data from one or more transmitters of the communicationsystem 1010 to one or more receivers of the communication system 1014,and vice-versa.

In some embodiments, the terminal 1012 can provide control data to oneor more of the movable object 1000, carrier 1002, and payload 1004 andreceive information from one or more of the movable object 1000, carrier1002, and payload 1004 (e.g., position and/or motion information of themovable object, carrier or payload; data sensed by the payload such asimage data captured by a payload camera). In some instances, controldata from the terminal may include instructions for relative positions,movements, actuations, or controls of the movable object, carrier and/orpayload. For example, the control data may result in a modification ofthe location and/or orientation of the movable object (e.g., via controlof the propulsion mechanisms 1006), or a movement of the payload withrespect to the movable object (e.g., via control of the carrier 1002).The control data from the terminal may result in control of the payload,such as control of the operation of a camera or other image capturingdevice (e.g., taking still or moving pictures, zooming in or out,turning on or off, switching imaging modes, change image resolution,changing focus, changing depth of field, changing exposure time,changing viewing angle or field of view). In some instances, thecommunications from the movable object, carrier and/or payload mayinclude information from one or more sensors (e.g., of the sensingsystem 1008 or of the payload 1004). The communications may includeinformation from one or more different types of sensors (e.g., GPSsensors, motion sensors, inertial sensor, proximity sensors, or imagesensors). Such information may pertain to the position (e.g., location,orientation), movement, or acceleration of the movable object, carrierand/or payload. Such information from a payload may include datacaptured by the payload or a sensed state of the payload. The controldata provided transmitted by the terminal 1012 can be configured tocontrol a state of one or more of the movable object 1000, carrier 1002,or payload 1004. Alternatively or in combination, the carrier 1002 andpayload 1004 can also each include a communication module configured tocommunicate with terminal 1012, such that the terminal can communicatewith and control each of the movable object 1000, carrier 1002, andpayload 1004 independently.

In some embodiments, the movable object 1000 can be configured tocommunicate with another remote device in addition to the terminal 1012,or instead of the terminal 1012. The terminal 1012 may also beconfigured to communicate with another remote device as well as themovable object 1000. For example, the movable object 1000 and/orterminal 1012 may communicate with another movable object, or a carrieror payload of another movable object. When desired, the remote devicemay be a second terminal or other computing device (e.g., computer, laptablet, smartphone, or other mobile device). The remote device can beconfigured to transmit data to the movable object 1000, receive datafrom the movable object 1000, transmit data to the terminal 1012, and/orreceive data from the terminal 1012. Optionally, the remote device canbe connected to the Internet or other telecommunications network, suchthat data received from the movable object 1000 and/or terminal 1012 canbe uploaded to a website or server.

FIG. 11 is a schematic illustration by way of block diagram of a system1100 for controlling a movable object, in accordance with embodiments.The system 1100 can be used in combination with any suitable embodimentof the systems, devices, and methods disclosed herein. The system 1100can include a sensing module 1102, processing unit 1104, non-transitorycomputer readable medium 1106, control module 1108, and communicationmodule 1110.

The sensing module 1102 can utilize different types of sensors thatcollect information relating to the movable objects in different ways.Different types of sensors may sense different types of signals orsignals from different sources. For example, the sensors can includeinertial sensors, GPS sensors, proximity sensors (e.g., lidar), orvision/image sensors (e.g., a camera). The sensing module 1102 can beoperatively coupled to a processing unit 1104 having a plurality ofprocessors. In some embodiments, the sensing module can be operativelycoupled to a transmission module 1112 (e.g., a Wi-Fi image transmissionmodule) configured to directly transmit sensing data to a suitableexternal device or system. For example, the transmission module 1112 canbe used to transmit images captured by a camera of the sensing module1102 to a remote terminal.

The processing unit 1104 can have one or more processors, such as aprogrammable processor (e.g., a central processing unit (CPU)). Theprocessing unit 1104 can be operatively coupled to a non-transitorycomputer readable medium 1106. The non-transitory computer readablemedium 1106 can store logic, code, and/or program instructionsexecutable by the processing unit 1104 for performing one or more steps.The non-transitory computer readable medium can include one or morememory units (e.g., removable media or external storage such as an SDcard or random access memory (RAM)). In some embodiments, data from thesensing module 1102 can be directly conveyed to and stored within thememory units of the non-transitory computer readable medium 1106. Thememory units of the non-transitory computer readable medium 1106 canstore logic, code and/or program instructions executable by theprocessing unit 1104 to perform any suitable embodiment of the methodsdescribed herein. For example, the processing unit 1104 can beconfigured to execute instructions causing one or more processors of theprocessing unit 1104 to analyze sensing data produced by the sensingmodule. The memory units can store sensing data from the sensing moduleto be processed by the processing unit 1104. In some embodiments, thememory units of the non-transitory computer readable medium 1106 can beused to store the processing results produced by the processing unit1104.

In some embodiments, the processing unit 1104 can be operatively coupledto a control module 1108 configured to control a state of the movableobject. For example, the control module 1108 can be configured tocontrol the propulsion mechanisms of the movable object to adjust thespatial disposition, velocity, and/or acceleration of the movable objectwith respect to six degrees of freedom. Alternatively or in combination,the control module 1108 can control one or more of a state of a carrier,payload, or sensing module.

The processing unit 1104 can be operatively coupled to a communicationmodule 1110 configured to transmit and/or receive data from one or moreexternal devices (e.g., a terminal, display device, or other remotecontroller). Any suitable means of communication can be used, such aswired communication or wireless communication. For example, thecommunication module 1110 can utilize one or more of local area networks(LAN), wide area networks (WAN), infrared, radio, WiFi, point-to-point(P2P) networks, telecommunication networks, cloud communication, and thelike. Optionally, relay stations, such as towers, satellites, or mobilestations, can be used. Wireless communications can be proximitydependent or proximity independent. In some embodiments, line-of-sightmay or may not be required for communications. The communication module1110 can transmit and/or receive one or more of sensing data from thesensing module 1102, processing results produced by the processing unit1104, predetermined control data, user commands from a terminal orremote controller, and the like.

The components of the system 1100 can be arranged in any suitableconfiguration. For example, one or more of the components of the system1100 can be located on the movable object, carrier, payload, terminal,sensing system, or an additional external device in communication withone or more of the above. Additionally, although FIG. 11 depicts asingle processing unit 1104 and a single non-transitory computerreadable medium 1106, one of skill in the art would appreciate that thisis not intended to be limiting, and that the system 1100 can include aplurality of processing units and/or non-transitory computer readablemedia. In some embodiments, one or more of the plurality of processingunits and/or non-transitory computer readable media can be situated atdifferent locations, such as on the movable object, carrier, payload,terminal, sensing module, additional external device in communicationwith one or more of the above, or suitable combinations thereof, suchthat any suitable aspect of the processing and/or memory functionsperformed by the system 1100 can occur at one or more of theaforementioned locations.

As used herein A and/or B encompasses one or more of A or B, andcombinations thereof such as A and B.

While some embodiments of the present disclosure have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the disclosure. It should beunderstood that various alternatives to the embodiments of thedisclosure described herein may be employed in practicing thedisclosure. Numerous different combinations of embodiments describedherein are possible, and such combinations are considered part of thepresent disclosure. In addition, all features discussed in connectionwith any one embodiment herein can be readily adapted for use in otherembodiments herein. It is intended that the following claims define thescope of the invention and that methods and structures within the scopeof these claims and their equivalents be covered thereby.

What is claimed is:
 1. An apparatus for controlling an attitude of apayload, comprising: a carrier comprising: a first frame, the payloadbeing affixed to the first frame; and a second frame rotatably coupledto a movable object; one or more first sensors disposed on the payloadand configured to measure one or more motion characteristics of thepayload; one or more second sensors disposed on the carrier andconfigured to measure one or more motion characteristics of the carrier;and one or more processors individually or collectively configured to:determine an input torque based on the one or more motioncharacteristics of the payload; determine an estimated disturbancetorque based on the one or more motion characteristics of the carrier;and calculate an output torque based on the input torque and theestimated disturbance torque, the output torque being configured toeffect movement of the second frame to achieve a desired attitude of thepayload.
 2. The apparatus of claim 1, further comprising: the movableobject; and a damping element disposed between the movable object andthe carrier; wherein the carrier is a multi-axis gimbal.
 3. Theapparatus of claim 2, wherein the second frame is coupled to the movableobject via the damping element.
 4. The apparatus of claim 3, wherein thesecond frame is coupled to the damping element via a coupling structure,and the one or more second sensors are disposed on the couplingstructure.
 5. The apparatus of claim 4, wherein the one or more secondsensors are provided on a flexible printed circuit (FPC) attached to thecoupling structure.
 6. The apparatus of claim 1, wherein the secondframe is coupled to a motor configured to rotate the second frame abouta yaw axis and the one or more second sensors are disposed on the secondframe or the motor.
 7. The apparatus of claim 1, wherein the estimateddisturbance torque is determined by inputting the one or more motioncharacteristics of the carrier into a predefined dynamics-based model ofthe carrier.
 8. The apparatus of claim 7, wherein the one or more motioncharacteristics of the carrier comprise at least a linear accelerationor an angular acceleration of the carrier.
 9. The apparatus of claim 7,wherein the one or more motion characteristics of the carrier areassociated with one or more motion characteristics of the second frame.10. The apparatus of claim 1, wherein the estimated disturbance torqueis calculated with respect to a rotatable joint on the second frame, therotatable joint being configured to couple the second frame to themovable object.
 11. The apparatus of claim 1, wherein the estimateddisturbance torque is refined using a proportional-derivative (PD)controller to obtain a refined disturbance torque.
 12. The apparatus ofclaim 11, wherein the estimated disturbance torque is refined byapplying one or more filters to the estimated disturbance torque. 13.The apparatus of claim 11, wherein the output torque is calculated basedon the input torque and the refined disturbance torque.
 14. Theapparatus of claim 1, wherein the input torque is determined using afeedback control loop.
 15. The apparatus of claim 14, wherein thefeedback control loop is implemented using at least oneproportional-derivative (PD) controller, the at least one PD controllercomprising a PD controller configured to calculate an output angularvelocity based on a difference between an instantaneous angle measuredby the one or more sensors on the payload and the input angle.
 16. Theapparatus of claim 15, wherein: the PD controller is a first PDcontroller; and the at least one PD controller further comprises asecond PD controller configured to calculate the input torque based on adifference between an instantaneous angular velocity measured by the oneor more sensors on the payload and the output angular velocity.
 17. Theapparatus of claim 1, wherein the output torque is calculated bycompensating the input torque with the estimated disturbance torque. 18.The apparatus of claim 17, wherein the output torque is calculated bysubtracting the estimated disturbance torque from the input torque. 19.The apparatus of claim 17, wherein the output torque is used inconjunction with an actual disturbance torque to effect the movement ofthe carrier to achieve the desired attitude of the payload.
 20. Theapparatus of claim 19, wherein the actual disturbance torque resultsfrom a disturbance to the carrier and is applied to the second frame.